Radiation curable compositions include reactive components such that a radiation induced curing reaction takes place on exposure of the composition to radiation, including Electron Beam (EB) radiation and actinic radiation, such as Ultra Violet (UV) radiation. The reactive components include functional groups which react with one another in the radiation induced curing reaction to form chemical cross-links thus providing a hardened cured film. Free-radical curable components include functional groups that cross-link under irradiation via a free radical mechanism to form a hardened film.
U.S. Pat. No. 5,756,829 (BASF) describes amine-modified epoxy (meth)acrylates that for use as radical-curable binders which are the product of (a) reacting an epoxy functional compound with acrylic acid and/or a methacrylic acid, and then (b) reacting the product of step (a) with a basic nitrogen compound such that the epoxy groups originally present are substantially completely reacted. For example, almost all of the epoxy groups in bisphenol A diglycidyl ether are reacted with acrylic acid, and then the remaining epoxy groups are reacted with an amine (mol ratio 0.01-0.2 amine:1 epoxy), such as ethanolamine or cyclohexylamine, to give an amine modified epoxy acrylate compound. Additional acrylate monomers can be added to reduce the viscosity.
East German patent DD 208365 describes high molecular weight, soluble addition polymers created by the reaction of a bisphenol A epoxy compound with a primary monoamine. The hydroxy groups formed by the ring opening reaction of the epoxides are then reacted with anhydride compounds such as acetic, methacrylic, acrylic or cinnamic anhydride. East German patent DD154985 describes similar high molecular weight soluble addition polymers in which aromatic diglycidyl ethers such as bisphenol A diglycidyl ether are reacted with various simple alkyl or aryl primary monoamines at a mol ratio of 1:1.
WO 2008/000696 (Cytec surface specialties) describes the reaction product by Michael addition of an epoxy acrylate oligomer (optionally diluted with a multifunctional monomer) with a simple primary or secondary amine such as ethanolamine, butylamine, or dodecylamine. The epoxy acrylate oligomer is a material which is the reaction product of an epoxy compound with the acrylic acid. WO 2006/131259 (Cytec surface specialties) describes the reaction product of Michael addition of an ethoxylated or propoxylated multifunctional acrylate monomer with a simple primary or secondary amine compound, such as butylamine, diethanolamine, diethanolamine, morpholine. Typically, this is to produce an aminoacrylate synergist capable of reaction with a Type II Photoinitiator. The preferred amines are alkylamines and dialkylamines, more particularly those where the alkyl group, each independently, comprised from 1 to 12 carbon atoms, preferably from 1 to 8 carbon atoms, optionally substituted by an hydroxy group.
There remains a need for new classes of oligomers suitable for use in radiation-curable compositions, such as UV or ER-curable inks, coatings and laminating adhesives.